JPS6370503A - Magnetic alloy powder and magnetic core using same - Google Patents

Abstract

PURPOSE:To provide a magnetic metal powder having a surface coating film of high insulation properties formed and a metal powder compression magnetic core providing a permeability which is flat till high frequencies by forming a coating film of a phosphate containing boron on the surface of each particle. CONSTITUTION:An amorphous alloy assumes a film or powder state when it is quenched very rapidly from its molten state. For instance, an amorphous magnetic alloy powder has formed on the particle surface thereof a phosphate coating film containing boron. To form the phosphate coating film, the amorphous magnetic alloy powder is dipped in a solution in which boric acid and phosphate were dissolved, and is subjected to a short-time treatment at a comparatively high temperature. The amorphous magnetic alloy powder having been completed in the surface treatment is then powder compression molded into a predetermined magnetic core shape. At that time, a small amount of glass or synthetic resin (polyimide) may be added, for instance, to an extent of 20wt.%, as a binder. Alternatively, a small amount of lubricant can be added to enhance the powder compression molding properties, in which a binder need not be used. The magnetic powder is thus improved in its properites due to the surface phosphate coating film of high insulation properties.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a magnetic alloy powder such as an amorphous magnetic alloy powder and a powder magnetic core using the same.

(Prior art and its problems) Amorphous magnetic alloys have excellent soft magnetic properties such as high magnetic permeability and low coercive force, so they have recently been researched for use in transformers, electric motors, yoke material inductors, and magnetic heads. Some parts have been put into practical use. These amorphous alloys have iron, nickel, and cobalt as basic metal components, phosphorus, boron, silicon, and carbon as metalloid elements, and, if necessary, other elements such as titanium, aluminum, zirconium, molybdenum, It is obtained by adding tank/l/, Cr, W, niobium, hafnium, etc., mixing to have a composition near the eutectic point, and ultra-quenching from a high temperature molten state.

Amorphous alloys are obtained as films, fibers, or powders, and in the case of films, they are ground into powders. To manufacture a magnetic core from these materials, a binder such as glass or epoxy resin is used and compression molding is performed. On the other hand, conventionally known soft magnetic alloy powders such as Permalloy and Seven Dust are mixed with S 10x 'P M g O as a binder and compression molded by applying a strong pressure of 10 to 20 t/m.

If a large amount of binder is used, the electromagnetic coefficient will decrease, so a small amount is generally used.However, conversely, there are more opportunities for amorphous metal particles to come into contact with each other, which reduces the electrical resistance of the green compact, and causes eddy currents to increase the high frequency side. In this case, the permeability increases and the permeability also decreases. Moreover, if the amount of binder is small, mechanical strength will be reduced.

In order to overcome the above-mentioned defects, it has been proposed to oxidize the surface of an amorphous alloy to form an oxide film (Japanese Patent Laid-Open Nos. 59-179729 and 60-26603).

Such an oxide film is formed on the surface of powder particles by charging amorphous alloy powder with water into an autoclave and treating it in an oxidized atmosphere at high temperature and high pressure with water vapor for several hours to several days. It is formed by prohibiting @@04, C0aOa, N l O, etc. It is reported that this improves the moldability of the powder and increases its magnetic permeability. In the case of an amorphous magnetic alloy whose main component is iron, the oxide film is F.,04
is the main subject. However, as is well known, F.,0. is a good conductor (so is C0,04, and NiO is Nl
However, the oxidation process requires equipment and a long time.

One of the inventors of the present invention has provided an amorphous magnetic alloy powder characterized in that a phosphate coating is formed on the surface of each particle, and a magnetic core made by compacting the same (patent application 60-1
No. 61163).

Since the powder has a highly insulating phosphate coating on its surface, it can stabilize the properties of amorphous magnetic alloys and prevent changes in properties over time due to oxidation caused by oxygen in the air, increasing reliability. It can be used in a wide range of applications as a magnetic core with high strength. Moreover, the phosphate coating can be formed in a short time using a simple process. Also, this powder has good moldability, so you only need to use a small amount of inorganic or organic binder (depending on the application, it may not be necessary to use it).
Since it can be made into a high-density magnetic core, it has a high magnetic flux density, and also has high insulation properties, which improves the Urahami microcharacteristics. The phosphates in this case were zinc phosphate, manganese phosphate, cadmium phosphate monocalcium phosphate, and iron phosphate. However, it has been found that powder magnetic cores using amorphous alloy powders coated with these materials do not have sufficient insulation properties and do not have sufficient magnetic properties in high frequency bands.

(Object of the Invention) Therefore, the object of the present invention is to provide a magnetic metal powder with a highly insulating surface coating and a metal powder magnetic core with good properties, and particularly to provide an amorphous magnetic alloy powder and a powder magnetic core. It is about providing.

(Summary of Structure and Effects of the Invention) The present invention provides a magnetic alloy, in particular an amorphous f.
Provided is a magnetic alloy powder and a magnetic core formed by compacting the same.

Since the powder of the present invention has a highly insulating boron-containing phosphate coating on its surface, it stabilizes the properties of magnetic metals such as amorphous magnetic alloys and prevents changes over time in properties caused by oxidation due to oxygen in the air. It can be used in a wide range of applications as a highly reliable magnetic core. Moreover, this phosphate coating can be formed in a short time using a simple process. Also, this powder has good moldability, so you only need to use a small amount of inorganic or organic binder (
(It may not be necessary to use it depending on the application), it has a high magnetic flux density because it can be made into a high-density magnetic core, and has low loss due to its high insulation properties, and has good frequency characteristics, and has a magnetic permeability of 7 rad up to high frequencies. can get.

(Detailed Description of the Invention) The amorphous magnetic alloy used in the present invention may have any known composition. As already mentioned, at least one of iron nickel and cobalt is used as a basic component, at least one of phosphorus, carbon, boron, and silicon is used as a semimetal, and if necessary, aluminum, titanium, phosphorus, At least one element selected from manganese, molybdenum, tantalum, vanadium, zirconium, steel, niobium, tungsten, thallium, rhenium, platinum, gold, silver, palladium, trisium, rubidium, hafnium, and rare earth elements is used. A preferred composition is one near the eutectic point between each of the two elements used. This amorphous alloy can be obtained in the form of a film or powder by ultra-quenching from a molten state using any known method. For example, it can be manufactured by various methods such as an atomizing method, a thermal spraying method, a single roll method, and a single roll method. When an amorphous alloy is obtained in the form of a film, it can be pulverized into powder after hydrogen embrittlement or other embrittlement treatment.

The obtained amorphous magnetic alloy powder is coated with a boron-containing phosphate coating on the particle surface according to the present invention. To form a phosphate film, amorphous magnetic alloy powder is immersed in a solution of boric acid and phosphate, and treated at a relatively high temperature for a short time. For example, in the case of zinc phosphate, 60 to 100
The treatment may be performed for several minutes to about 30 minutes using an aqueous solution with a concentration of several percent heated to .degree. As a result, a film of phosphate is deposited on the surface of the amorphous magnetic alloy particles.

The amorphous magnetic alloy powder that has undergone the surface treatment is then compacted into a predetermined magnetic core shape. At that time, a small amount of glass or synthetic resin (polyimide etc.) is used as a binder, for example 2
It may be added up to about 0vt%. Alternatively, a small amount of lubricant can be added to increase the compactability, in which case no binder is needed.

The magnetic powder of the present invention has improved stability, high electrical resistance, and moldability due to the highly insulating surface phosphate coating. Furthermore, the permeability of the magnetic core can be increased, and the high frequency characteristics can also be improved.

It has not been confirmed in what form boron is contained in phosphate, but as mentioned earlier, boric acid and phosphate dissolved in water are mixed together on the surface of magnetic particles. Although it depends on the type of phosphate, it is preferable that the ratio of BPO4/metal phosphate is [1001 to α1 (α1 to 10 Wt, child %) in terms of phosphate (BPO4). . It has been found that when it is within this range, the grain boundaries of the phosphate coating become small and uniform, resulting in a dense and highly insulating coating. Surface texture can be easily observed with a microscope. If this ratio is smaller than 1/1000, there will be no effect;
If it is larger than 10, the film thickness of the film becomes thick and the initial permeability of the molded article deteriorates. As the metal phosphate, the aforementioned manganese phosphate, zinc phosphate, calcium phosphate, cadmium phosphate, and iron myphosphate can be used. Among these, manganese phosphate provides a dense and highly insulating film, while zinc phosphate provides high magnetic permeability although it is less dense, has lower electrical resistance, and has poorer high frequency characteristics. Therefore, for high frequencies, use Mn-based or Zn-Mn yarn, and improve the characteristics with boron, and if high frequency characteristics are not a problem, add boron to the Zn yarn, and it will be 7. A smooth magnetic permeability is obtained, and iron loss due to eddy currents is also reduced.

The present invention will be explained below using examples.

Example 1 An amorphous alloy ribbon having a composition of F@ylSigB1s was pulverized into a flaky powder of 20 to 80 meshes.

A 4% zinc phosphate aqueous solution was prepared, boric acid was added thereto, and the temperature was raised to 95 to 99°C.

The amorphous alloy powder was immersed in this liquid and treated for about 20 minutes to form a lead phosphate-boron phosphate coating on the powder surface.

Thereafter, it was dried in hot air to obtain the desired magnetic powder. Chemical analysis of this coating revealed that boron phosphate was α5a.
It contained t%.

Add 2v of enriched poron to the powder thus obtained as a lubricant.
Add t%, charge into a mold, and heat at 460°c1800MP.
Under the conditions of a, powder compaction was performed for 1 minute to obtain an outer diameter of 25 mm.
A toroidal magnetic core having an inner diameter of 1 gmm and a thickness of 5 mm was obtained. A conducting wire was wrapped around this in a film shape and the magnetic properties were measured. Table 1 shows the results.

Example 2 Boric acid was added to a 10% manganese phosphate aqueous solution, and 82~
The temperature was raised to 85"C, and amorphous alloy powder was added and treated for about 10 minutes to form a manganese phosphate-boron phosphate film on the powder surface. Chemical analysis of this film revealed that phosphoric acid It contained 12 at % of boron.The alloy powder was dried in hot air to obtain the intended magnetic powder.

The same treatment was carried out by changing the amount of boric acid added to obtain magnetic powders containing 3 at% and 9 at% of boron phosphate, respectively. These powders were molded in the same manner as in Example 1 and their magnetic properties were measured.

Comparative Example 1 A toroidal core was manufactured by adding 12 at% of boron phosphate in Example 2. The results are shown in Table 1.

Comparative Example 2 Comparative Example 2 was obtained by producing a toroidal core without adding boron in Example 1 above. The measurement results are shown in Table 1.

Comparative Example 3 A toroidal core was prepared in the same manner as in Example 2 without adding boron. Table 1 shows the results.

Example 3 A toroidal core was produced in the same manner as in Example 1 except that Sendasuji powder was used instead of the amorphous alloy. Table 2 shows the results.

Comparative Example 4 In Example 3, a magnetic powder with a zinc phosphate coating and a toroidal core therefrom were produced without using boron phosphate. Table 2 shows the results.

As can be seen from the table of results, the iron loss value becomes extremely small due to the inclusion of boron phosphate, and stable characteristics are obtained especially at 11 to 10 at%. However, when it exceeds 10%, the value of initial magnetic permeability becomes small and the value of iron loss increases. From this, the boron phosphate contained in the coating must be greater than α1% and less than 10%.

(Summary of effects) As described above, according to the present invention, the iron loss of the magnetic alloy powder is reduced by using a phosphate coating containing boron, and the magnetic alloy powder has a flat initial permeability with little frequency dependence. Magnetic powder and dust core can be obtained.

Claims (6)

[Claims] 1. A magnetic alloy powder characterized by forming a coating of metal phosphate containing boron on the surface of the particles. 2. The magnetic alloy powder according to item 1 above, wherein the metal phosphate is selected from zinc phosphate, manganese phosphate, cadmium phosphate, calcium myphosphate, and iron phosphate. 3. Boron is converted to boron phosphate, which is 0.0% of phosphate.
The magnetic alloy powder according to the above item 1 or 2, containing 1 to 10 atomic %. 4. A powder magnetic core formed using magnetic alloy powder with a coating of metal phosphate containing boron on the surface of the particles. 5. 5. The powder magnetic core according to item 4, wherein the metal phosphate is selected from zinc phosphate, manganese phosphate, cadmium phosphate, calcium phosphate, and iron phosphate. 6. Boron is converted to boron phosphate, which is 0.0% of phosphate.
The magnetic alloy according to the above item 4 or 5, containing 1 to 10 atomic %.